This invention relates generally to communicating data. More particularly, this invention relates to communicating data on signals that are normally static, such as configuration jumper signals.
Many electronic devices have a communication channel that is used for development, diagnostic, and production functions. For example, a disk drive may have an RS-232 interface connected through a DB-9 connector so that a firmware developer can monitor the internal state and functioning of the disk drive. This same interface may also be used later in a production environment to initiate and monitor a final self-test sequence before packaging and shipping the device to a consumer. Unfortunately, a large connector, such as a DB-9 or DB-25, is unsightly, adds cost, and may be difficult to find room for on the product. Furthermore, it may be desirable to discourage the end user from accessing this interface. The connector can be hidden, and access prevented by placing the connector underneath the case, or skin, of the product. However, if the connector is hidden in this way, it is inaccessible when the product is completely assembled. This makes it impossible to access the communication product after a certain stage of manufacture, and impossible to access when the product is being used in it""s intended manner.
Accordingly, there is a need in the art for a communication channel that can function after a product is entirely assembled, but does not advertise its presence. It is desirable that this channel not necessarily require an additional connector. Such a channel should also be capable of communicating both serial and parallel data in both directions. Finally, such a channel should be capable of implementation using existing features that are accessible from the outside of a filly assembled device.
The invention provides a communication channel that is accessible when the product is entirely assembled, but appears to be, and functions like, configuration jumpers to the end user. This communication channel requires only a small number of additional parts, and possibly even saves money by eliminating the need for a large, expensive connector on each device. The invention is readily adaptable to a variety of interfaces, both standard and non-standard.
An embodiment of a communication channel according to the invention utilizes the terminals of a configuration jumper block as communication paths to an interface device. The terminals of the configuration jumper block may be wired differently depending on the desired function (i.e. send data, receive data, etc.) of the terminals. The configuration information needed by the device is read from the terminals of the configuration block when the communication channel is not active. Switches on the interface device are used to set the configuration information.